Chironex may be
found in shallow water at the edge of beaches in Northern Australian and
Indo-Pacific region. Adult jellyfish spawn at river mouths in late summer.
The fertilized eggs attach themselves to rocks in the form of tiny polyps.
In spring, these polyps develop into small jellyfish that migrate downstream,
especially with rains. They feed on shrimps and often frequent beaches
that are attractive to humans. These animals have chosen a strategy of
passive hunting- they simply wait for the prey to bump into their tentacles.
Since a struggling shrimp can tear a young jellyfish, it needs to be killed
instantly with a very strong poison.
corner of the box-shaped bell, often as large as a basketball, there is
a bundle of ten to sixty stinging tentacles, which can extend for up to
The body of a sea
wasp can weight as much as 2 kg. The tentacles are armed with up to 5,000
or stinging cells. Certain chemicals on the surface of fish, shellfish
and humans activate these. Contact with only 3 m of tentacles may be fatal
for an adult. There are many (about 70) reported deaths that have occurred
in northern Australia between November and April.
invisible in seawater
According to recent discoveries,
the box jellyfish is able to see through four eyes, one at the center of
each side of the bell. It is not known how the animal processes the visual
information without a brain. However, it avoids even the tiniest objects.
Box jellyfish probably try to avoid humans as well; stings usually occur
when people bump into them. An interesting fact is that turtles are not
affected by their sting and eat them.
quadrigatus, is generally less common than Chironex fleckeri,
though it may prevail in some places. It is smaller, with slimmer tentacles
but very much resembles the sea wasp. The box jellyfish is, however, the
most lethal member of its family.
Symptoms and first aid
The venom of box jellyfish
has cardiotoxic, neurotoxic and highly dermatonecrotic components. When
injected, it is rapidly absorbed into the circulation. The pain is excruciating;
the tentacles become sticky and adhere tightly to the skin. Any attempt
at removal of the tentacles while they are still active may worsen the
sting and lead to great injuries. Severe stings result in necrosis of the
affected skin area. If treatment is not given, the pain may last for weeks
and often stings leave significant scars.
Domestic vinegar (never methylated
spirits) should be poured over the adhering tentacles to inactivate nematocysts
as quickly as possible. When the tentacles become inactive, they can be
safely removed. (The application of vinegar is not intended to decrease
pain or diminish the effects of the venom; it will only stop further discharging
of nematocysts). In case of respiratory or
basic life support such as artificial respiration and cardiac massage is
necessary. Where antivenom is not available, pressure-immobilization of
the limbs may be used after inactivation of nematocysts while the patient
is transported to hospital.
Indications for antivenom
include cardiorespiratory arrest or arrythmias, difficulty with breading,
speech or swallowing and extensive skin lesions. Assisted ventilation and
analgesics may be needed. Early administration of antivenom will reduce
and decrease scarring. Local
pain is usually best treated with ice packs.